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Darwin Correspondence Project

From Thomas Rivers   30 January 1863

Nurseries, Sawbridgeworth, Herts, | Great Eastern Railway.

Jany 30/63

My dear Sir/

I am now going to pester you with a question.1 In the cultivation of peach trees in enclosed houses I have found that they cannot be kept in health unless the fresh air is admitted so that it enters at a lower level & makes its way under the leaves as at a

[DIAG HERE] Mem the lines [DIAG HERE] are to be supposed the two walls of a house

rising as it becomes rarefied by the heat of the house, & that air admitted at the upper part of the wall of a glass roofed house as at b will not keep peach trees in health   this has induce〈d〉 me to think that the lungs 〈of〉 the leaves (so to speak) are on the under surface— there is as you know much difference in the appearance of the two surfaces. Now can you by employing a powerful microscope & your power of mind do anything for me in this matter?

Referring to my last2 I was brought to my, I fear, idle reasoning on the effects of soil & climate on our race by observing for several years past English gardeners & nurserymen visiting here who had lived from seven to ten years in the United States of America some from the far west others in the sea-board states with only one exception & he was a Scotchman, I remarked that in their features & figures they had assumed the genuine American type the cheekbones in most cases high the nose thin & if in the least inclining to the aquiline this peculiarity much agravated. the cheeks hollow the eyes sunken everything belonging to them reminding one of the normal Indian race. I have often expressed my surprise to those men that soil & climate would have so changed them & they have admitted that they felt a change not only in their persons but in a rush of fierce energy unknown to us at home.

These facts are all straws but they may give a hint however trifling to your reasoning powers

I am My dear Sir | Yrs. very truly | Thos. Rivers

CD annotations

On cover: ‘Weeping Trees’ ink


CD began a correspondence with Rivers at the end of 1862, first inquiring about bud-variations (see Correspondence vol. 10, letter to Thomas Rivers, 23 December [1862]).


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 27 vols to date. Cambridge: Cambridge University Press. 1985–.


Asks CD’s views on TR’s observations that leaves breathe from their under-surfaces.

Peach-trees in hothouses cannot be kept in health unless fresh air is admitted so as to make its way under the leaves.

Continues his observations on the effect of environment on men – those migrating to America gradually assuming Indian-like features.

Letter details

Letter no.
Thomas Rivers
Charles Robert Darwin
Sent from
JA 30 63
Source of text
DAR 176: 162
Physical description
3pp †

Please cite as

Darwin Correspondence Project, “Letter no. 3955,” accessed on 27 October 2020,

Also published in The Correspondence of Charles Darwin, vol. 11